Question:

Consider the following code snippet:

public class ScopeExample {
    public static void main(String[] args) {
        int a = 5;
        int b = 10;
        int result = multiply(a, b);
        System.out.println("The product is " + result);
    }

    public static int multiply(int x, int y) {
        int result = x * y;
        return result;
    }
}

Analyzing the code snippet above, answer the following questions:

a) Explain the concept of scope in Java.

b) Identify the variables in the code snippet and their respective scopes.

c) Determine the lifetime of each variable in the code snippet.

d) In the multiply method, what happens if we try to access the variable result outside its scope?

Provide comprehensive explanations for each question above.

Answer:

a) Scope in Java refers to the region of code where a variable or identifier is accessible. It defines the portion of the program where a variable can be used or accessed. The scope determines the visibility and lifetime of a variable.

b) In the given code snippet, the variables and their respective scopes are as follows:

• a and b are local variables declared inside the main method. Their scope is limited to the main method.
• result is a local variable declared inside the multiply method. Its scope is limited to the multiply method.

c) The lifetime of each variable in the code snippet is as follows:

• a, b, and result are method-local variables, which means they are created when the method is invoked and are destroyed when the method execution completes. Therefore, their lifetime is limited to the duration of the method execution.

d) In the multiply method, if we try to access the variable result outside its scope (i.e., after the return statement), a compilation error will occur. This is because a variable declared within a specific scope is not accessible outside that particular scope. Once the method completes, the variable result is destroyed, and its value is no longer available.

To illustrate, consider modifying the code as follows:

public class ScopeExample {
    public static void main(String[] args) {
        int a = 5;
        int b = 10;
        int result = multiply(a, b);
        System.out.println("The product is " + result);

        System.out.println("The result outside multiply method is " + result);
        // Error: The variable 'result' cannot be resolved to a variable
    }

    public static int multiply(int x, int y) {
        int result = x * y;
        return result;
    }
}

In this modified code, trying to access result outside the multiply method results in a compilation error, indicating that the variable result is not accessible in the scope of the main method.

This restriction ensures the encapsulation of variables and prevents unintended changes or misuse of variables outside their intended scope.